1. Field of Use
The invention includes embodiments that relate to a cathode composition with one or more additive for use in an electrochemical cell, and an energy storage device including the same.
2. Discussion of Art
Electrochemical cells are known which include a molten alkali metal (such as sodium) negative electrode or anode; an electrically insulative solid separator which functions as an alkali metal ion-conducting solid electrolyte; a salt electrolyte in the positive electrode compartment which is at least partially molten at the operating temperature of the cell; and a positive electrode. These have been referred to as sodium-metal halide cells or batteries. Electrochemical cells of this type are useful as power sources or energy storage devices.
For mobile applications such as hybrid locomotives or plug-in electric vehicles (PHEV), it is desirable for a sodium-metal halide battery to be able to tolerate power surges (i.e., high currents) during both battery charging and discharging, without significant loss in the working capacity and the cycle life. In particular, for mobile applications attempting to provide better fuel economy via regenerative braking, this betterment in electric efficient is desirable. One known way to attempt improvements in cell performance of sodium-metal halide cells, is by addition of a small amount of elemental sulfur to the cathode composition.
However, there continues to remain a need for new additives to solve the problems of high current cell performance, to improve the cell working capacity and decrease the capacity degradation rate.